The mechanical properties, fracture toughness, fracture surface morphology, and failure mechanisms of different layers in a premium railhead were studied. Correlation between the mechanical properties and the failure mechanisms for each of the layers was made. It has been found that the microstructure and mechanical properties of the top layer are different from those of the inner layers, while the middle layer and the layer near the web demonstrated similar mechanical properties, microstructure, and fracture toughness. The top layer displayed 15% higher tensile strength than the other two layers. However, the strain to failure of the top layer, 11%, is only about 60% of that of the inner layers, 17.5%. The top layer has a fracture toughness, KIc, of 75 MPa m1/2. This value for the inner layers is about 95 MPa m1/2. Thus, the heat treatment decreases the ductility and fracture toughness of the top layer of the railhead. Transition from the brittlelike fracture mechanism of the top layer into a more ductile mechanism of the inner layers was also found.
Microstructure origin of strength and toughness of a premium rail steel
Journal of Materials Engineering and Performance ; 10 , 3 ; 331-336
2001
6 Seiten, 26 Quellen
Article (Journal)
English
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